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Warm Apple Crumble in Cast Iron Skillet |
Introduction
The perfect apple crumble is, first and foremost, a contrast of textures: a custard of spiced, jammed-down fruits, beneath a jagged, buttery, and hugely-crisp streusel of oats and sugar. To achieve such a contrast typically involves cooking apples down for hours in the oven, their rigid cell walls slowly breaking down into a soft, syrupy paste. But by using a dual-zone oven, and cooking the fruit and topping simultaneously for a just twenty minutes, it’s entirely possible to coax the same deep, caramelly flavors from the apples, as well as a crust that’s retaining its crunch.
A perfect apple crumble is all about contrast – soft, jammy, spicy apple pulp beneath a jagged crust of buttery, crunchy streusel made from oats, flour and sugar. The fruit must have been broken down by long, slow baking in the oven to create the necessary pulpy consistency. This structure can be achieved in a short time by using a dual-zone oven, so that the apples can reach the same depth of flavor and the topping can remain crunchy in just 20 minutes. The flavors within the apple crumble are of the highest contrast – the sweet and tart of the apple, the molasses-like warmth of the brown butter and dark sugar, which have created a deep and complex flavor during cooking. These are then cut by the fresh, vegetal, bitter notes of matcha ice cream, which add a cool contrast to the hot dessert. Apple crumble is a classic autumn dessert, but it is so quick to make that it can also be served as an impressive finale to an impromptu dinner party at any time of year.
Ingredient Deep-Dive & Smart Substitutions
The Apples
Selection & Function: Use firm, heavy-for-their-size apples. Use 300g / 2 medium Granny Smith apples and 300g / 2 medium Honeycrisp apples. These apples have the best structure and the most pectin to hold together in cooking. The sharp acidity of the Granny Smith apples is balanced by the floral sweetness of the Honeycrisp apples. Both apples retain their pleasant toothsome crunch after cooking. Choose apples with taut skins and avoid those with bruising or soft spots.
Substitutions: In place of the two Granny Smith or Honeycrisp apples, two Braeburn or Jonagold apples could be substituted. Bosc pears ( firm) would also make an excellent grain-free substitute for this recipe using identical technical guidelines.
The Sugars
Preparation & Function: Muscovado or dark brown sugar (100 g / 1/2 cup packed) adds moisture and flavour of caramel and molasses which transforms into glossy fruit syrup as it liquefies. Granulated white sugar (50 g / 1/4 cup) is used for crumble as it will aid in moisture evaporation and crumble formation.
Substitutions: In place of white sugar, we use coconut sugar, which is lower in glycemic index and brings to the cake a rich toffee-like flavor.
The Fats
Selection & Function: We use unsalted European-style butter (115 g / 1/2 cup or 1 stick) that has a minimum of 82% butterfat. Regular butter has a high water content which will cause the flour to steam instead of fry and lead to a crumble that does not have the desired crunch.
Substitutions: Vegan or dairy-free adaptations may be achieved by substituting with high-quality block-style plant butter or refined coconut oil that has been solidified in the refrigerator.
The Flour and Oats
Selection & Function: This streusel is made with unbleached all-purpose flour (95g / 3/4 cup) to form the base of the streusel and the rolled old-fashioned oats (60g / 2/3 cup) to add the rough texture and nutty flavor. Please do not use instant oats as they become paste like.
Substitutions: Use a 1:1 ratio of gluten-free all-purpose flour or oat flour/almond flour blend. Make sure to use gluten-free rolled old-fashioned oats as well and look for certified gluten-free status.
Essential Equipment
10- Inch Cast-Iron Skillet: The largest piece of cookware in our arsenal, the superior thermal mass of cast-iron cookware allows for a transition from stovetop to dry heat of the oven, maintaining the ambient energy for the fruit filling to gel during the baking process.
Instant-Read Digital Thermometer: Check that the interior temperature of the filling has reached the proper gelling temperature for gelatinization.
Pastry Cutter or Chilled Fingertips: Use to rub cold fat into flour to make a pastry dough without melting butter solids.
Step-by-Step Professional Method
1. The Meticulous Prep
To make the apples, preheat the oven to 218°C (425°F). Next, peel, core and cut the apples into very small, and uniform 1.5cm or 1/2 inch cubes. The uniformity of the cubes is crucial as unevenly cut apples can mean that parts of the apples are far too mushy or uncooked and quite unpleasant.
2. The Stovetop Par-Cook
Heat a cast-iron skillet over medium-high heat. Add the butter and melt it. Once it has melted and formed a foam, allowed the foam to subside and it has begun to develop a nutty flavor but not yet a burnt flavor, remove the skillet from the heat. Add the apples, dark brown sugar, vanilla, cinnamon and salt to the skillet and toss to combine. Return the skillet to the heat and cook, stirring frequently, until the apples have developed a translucent border but are still firm in the center, about 5 minutes. The sugar will draw the juices from the apples and combine with the melted butter to form an emulsified, bubbly glaze.
3. Engineering the Streusel
While the apples are par-cooking, mix the flour, rolled oats, granulated sugar and a pinch of salt in a chilled bowl. Then work in the remaining 85g (3/8 cup) cold butter cut into small cubes. You should be working quickly to keep the mixture cold and it should have a slight tackiness to it, but must not become greasy or warm. It should look like coarse gravel with pea-sized clumps.
4. The Assembly and 20-Minute Bake
Remove the skillet from the heat and spread the streusel topping evenly over the apples. There should be a few “holes” around the edges of the streusel to allow for the syrup to flow out in bubble form. Place the skillet directly in the oven, on the center rack.
Bake for 18 to 20 minutes and keep checking on it through the oven window. You will know that it is done when the streusel topping has turned a deep golden brown color. Also, make sure that the syrup from the apples at the edges of the skillet is bubbling lazily. Remove from the heat and let cool for 5 minutes and then serve. This will allow the molten sugars to cool down a bit and allow the flavors to develop.
The Science Behind the Recipe
Secret #1 to getting the apples to be baked in only 20 minutes is controlling starch gelatinization as well as evaporation of the apples’ moisture. Raw apples are full of air spaces as well as very tight lathwork of cells which are held together with pectin. When we par cook the apples in the very conductive cast-iron skillet used for this dessert, much of the apples’ pectin is broken down as well as the apples’ bound water released from the cells. This allows for quicker gelatinization as well as evaporation of the apples’ moisture in the hot oven.
The Maillard reaction and the sucrose caramelization will develop rapidly on the surface of the streusel during baking at high temperature (218°C / 425°F). In the meantime, the flour in the streusel layer absorbs the steam rising from the apples and, while it is escaping, it forms a number of very thin starch gels. As the remaining moisture from the apples evaporates, these gels will set into a crisp structure, thus ensuring that the topping will be baked through without the underlying fruit turning to a soupy purée.
Pro Tips for Success
Freeze Your Topping: For the best streusel possible, pop your mixed crumble topping in the freezer for 10 minutes before you spread it on top of your hot fruit. The sudden change in temperature gives the worst effect of thermal shock to the butter in the streusel and it will not melt as quickly in the oven. This will allow for the best definition and create the most ultra-crisp pockets of streusel throughout the crumble.
The Acid Counterbalance: Mixing the raw apples with 5 mL (1 tsp) of freshly squeezed lemon juice before cooking them helps to stabilize the pectin in the apples, and contrastes with the sugar in the baked filling.
Common Mistakes to Avoid
Not making the apples fine enough, or too many of them fitting into the pan: The apples turn to baby food and the bottom of the topping goes all soft.
Using Warm Butter: If the butter gets too warm during mixing, the resulting streusel will end up as a hard, greasy, single mass instead of a light and fluffy of separate and crunchy bits.
Culinary Safety & Hygiene
Always wash apples in cold water to remove any surface residue before peeling. As filling reaches over 100°C (212°F) during baking, care must be exercised when removing the heavy cast-iron skillet from the oven and the handle will remain hot for some time. A dry, heavy oven mitt is recommended.
The Perfect Pairing
The bitterness of the premium Japanese Uji matcha ice cream is a beautiful contrast to the buttery flavor of the oat streusel in this apple crisp. As the cold ice cream starts to melt into the warm spiced apple syrup it creates a beautiful and complex sauce to dip your crisp into. A roasted medium oxidized oolong tea or a dry sparkling hard cider would also pair beautifully as they bring out the orchard flavors of the apples and help to cut the richness and clean the palate between bites of crisp.
Storage & Reheating Excellence
Refrigeration: Left overs will keep for 3 days if kept in an airtight container.
Freezing: Frozen baked crumble can remain safe and of best quality for up to 1 month in the freezer. Allow to defrost thoroughly in the fridge before warming up.
Reheating: We wouldn’t recommend heating in the microwave as it will make the streusel part all soggy. Warm up the whole crumble in a 175°C (350°F) oven for 8-10 minutes. The base will be bubbly and the topping all crispy on top.
Frequently Asked Questions (FAQ)
Can I make the crumble topping in advance?
Yes. The unbaked streusel is best made just before, but it can be stored in an airtight bag in the refrigerator for up to 5 days. It can also be frozen for up to 3 months and then baked straight from frozen. Allow 2-3 minutes extra in the total cooking time.
Why is my apple crumble soggy?
A soggy bottom on your apple crumble could be down to a couple of reasons: the fruit in the apple crumble releasing a lot of moisture during baking that hasn’t had a chance to evaporate, or that the apples haven’t been baked at a high enough temperature for a long enough time. To make the most of your apples, make sure you’re baking them at 218°C/425°F (using a cast-iron skillet is particularly effective here as it holds and releases moisture early) and adjust the cooking time as necessary.
Which matcha grade is best for the ice cream it is paired with in the desserts on this website?
For the ice cream accompanying the apple crumble I would recommend either a high-end culinary grade matcha or a lower-end ceremonial grade matcha. A lower quality matcha can give an unpleasant muddy taste and even an unpleasant bitter taste whereas the higher quality matcha’s will give a bright, vibrant green color and a clean taste of astringency with a umami taste that is balanced by the sweetness of the dessert.
Nutrition Facts
Has anyone attempted to implement this accelerated method of cooking apples in a skillet? I am curious to find out how your chosen apples performed in terms of texture. Please describe your results in the kitchen, ask technical questions here in the comments, or go to the comments section to discuss and share your favorite seasonally inspired interpretations.
